No, it doesn't ruin everything, it makes it better. HL2 is rendered so that it is optimized for your left and right screens to be steeply angled relative to the center screen. By this I mean that the angle from the center screen should be 45 degrees or more. This wraps the view around your head and extends the virtual peripheral vision into your real peripheral vision.
Some games require more screen angling than others. The more angle required, the stranger screenshots look when they are displayed in a single flat plane.